title: An on-line computer system for monitoring respiratory and cardiac functions of patients.
abstract: A computer-based noninvasive and continuous patient monitoring system for breath-by-breath assessment of cardiorespiratory functions was developed. Transthoracic impedance changes caused by respiratory and cardiac activities were measured with separate impedance plethysmographs of different frequencies. A mini-computer system calculated on-line eight respiratory parameters (VT, f, VE, PETO2, PETCO2, VO2, VCO2, and R) in cooperation with expired gas analysis data from a mass-spectrometer, and three cardiac parameters (SV, HR and Q). These parameters were displayed simultaneously at the end of each breath. In order to improve the signal-to-noise ratio of the impedance cardiogram to a level allowing computer determination, an ensemble averaging technique was utilized. The computer-derived cardiorespiratory parameters obtained during voluntary hyperventilation and a passive tilt demonstrated reasonable changes.
mesh_terms: D002245:Carbon Dioxide; D002307:Cardiography, Impedance; D003201:Computers; D004562:Electrocardiography; D006321:Heart / Q000502:physiology*; D006334:Heart Function Tests; D006801:Humans; D008168:Lung / Q000502:physiology*; D008905:Minicomputers; D008991:Monitoring, Physiologic / Q000379:methods*; D010100:Oxygen; D010992:Plethysmography, Impedance; D012119:Respiration; D012129:Respiratory Function Tests
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen